How Blood Flow Restriction (BFR) Training Works

By: Isaac Landrith, CSCS, SDPT1-OUHSC

BFR stands for blood flow restriction. This is a method of training used to illicit metabolic stress and attain hypertrophic effects, strength gains, and improvements to aerobic capacity at a lower intensity compared to traditional high-intensity training.

After reading this, you will know what BFR training is, the benefits of BFR training, and the proper implications for BFR training.  

How does BFR work?

BFR training involves a pressurized or elastic cuff around the arms or legs that reduces the amount of arterial inflow to the muscle while also occluding venous blood return. This creates a hypoxic environment in the muscle, forcing it to work with low oxygen availability.

This accelerates metabolic buildup and the accumulation of metabolites such as lactate and inorganic phosphate. Due to the hypoxic environment, the aerobic type I muscle fibers fatigue quicker, causing the recruitment of anaerobic type II muscle fibers.  

There are a few important distinctions between BFR training, BFR, and practical blood flow restriction (pBFR):

• BRF uses an electric pressured cuff, and pBFR is used with elastic cuffs that are manually tightened:
  • BFR cuffs are more reliable and accurate but have a much greater financial cost
  • On the other hand, pBFR cuffs are much cheaper and easier to use with large groups of individuals. Still, they are not as accurate and may become unreliable due to the elastic material wearing down over time

What are the benefits of BFR/pBFR?

There are many benefits, with the largest being the ability to illicit benefits such as muscle hypertrophy and strength gains similar to that of traditional high-intensity training (HIT) while providing less mechanical stress and less muscle damage.

BFR training can allow for the recruitment of high threshold motor units without the neural stress that HIT does. BFR training has also been shown to have a large acute stimulation of growth hormone (GH) post training.

A research study showed that those who trained at 80% 1 RM without BFR showed 100 times increase in plasma GH whereas those who trained at 20% 1RM with BFR showed 290 times increase in plasma GH (4). BFR has also been shown to have aerobic benefits such as increased VO2Max. A study was conducted comparing a BFR group who cycled for 15 min at 40% VO2Max compared to a non BFR group who cycled at 40% VO2Max for 45 minutes. The study showed that the BFR group had a significant increase in aerobic capacity compared to the non BFR group (1).  

Who can benefit from BFR training?

BFR training can benefit a large array of individuals. Specifically, those who are in post-op rehabilitation and athletes of all sorts. Those who are in post-op rehab can see a great benefit to this training, and it is scalable to any stage of their rehab. They can start using BFR cuffs while they are on bed rest or immobilized, and has been shown to decrease the amount of muscle atrophy (3,5).

BFR is great for athletes who are in the offseason in a general preparatory phase or when in a deload week (3).  

When is BFR not safe to use?

There are some contraindications to be aware of when you are implementing BFR training. Those include people who may have high blood pressure, deep vein thrombosis, cardiac disease, women who are pregnant, varicose veins, or rhabdomyolysis. Be cautious and stop BFR training if symptoms such as numbness, feeling cold, or subcutaneous hemorrhages arise (4).

How can you properly use BFR cuffs?

BFR cuffs can be used bilaterally or unilaterally and are going to be used on either the upper extremities or lower extremities. For example, for a squat movement you would use the cuffs on proximal portions of your thighs. For an upper body movement like a bicep curl, you would place them on the proximal portion of your arm.

It is also important to select the right size cuff for exercise. You need to measure the circumference of the limb you will be using this application on. For example, for an upper body movement, you would measure the circumference around the proximal portion of your arm, and for a lower body movement the proximal portion of your thigh.

• Most BFR cuffs come in a small (8”-13”), medium (13”-18”), large (18”-24”), and sometimes x-large (24”-29”) cuff.

You also need to select the correct width of the cuff. These also are usually in sizes of small (5cm), medium (10-12cm) and large (17-18cm). The larger cuffs can restrict arterial blood flow at lower pressures than smaller cuff sizes such as the 5cm width cuffs.

With that in mind it is useful to use the wider cuffs on extremities that are wider in circumference that need more pressure to occlude arterial blood flow. It is mostly recommended to use a wider cuff regardless of choosing upper or lower extremity so that the pressure is more evenly distributed and can be safer for the athlete.

Limb Occlusion Pressure

You need to find the individual's proper limb occlusion pressure (LOP). This is useful when using automating BFR cuffs versus the manual pBFR cuffs. The pBFR cuffs are tightened on a “perceived” tightness scale. LOP can be found by using the BFR cuff or a basic blood pressure cuff.

You will be palpating the radial artery for the upper extremity and the posterior tibial artery for the lower extremity and can use an ultrasound Doppler for a more accurate measurement.

The process is as follows:

1. Place the BFR or blood pressure cuff around the extremity you will be exercising and find the desired artery.
2. Once you find a strong pulse you will begin to slowly inflate the cuff and stop inflating when the pulse is completely diminished.
3. Once you have done that take note of the pressure and use that as you proceed with the exercise (4).

How can we program BFR?

BFR isn't the same for everyone. Each individual's goals will determine the approach used to elicit the most specific response, which can lead to improved training outcomes. It can be helpful to look at a BFR protocol for 3 different goals:

• BFR for resistance training
• BFR for aerobic capacity
• BFR for muscle atrophy prevention

BFR for Resistance Training

If you are using this for more than 3-week period you can use this 2-3 times per week, if using this for up to 3 weeks you can do this 1-2 times per day.

• For a BFR cuff use a 40-80% AOP or 6-7 tightness on a 1-10 scale. Occlude the muscle group for 5-10 minutes per exercise and allow for reperfusion between exercises.
• Prescribe 2-4 sets with 30-60 seconds of rest between sets at 20-40% 1RM.
• You want to perform up to a total of 75 reps per exercise.
• A typical rep scheme would be 30-15-15-15 with a 1-3 second controlled concentric and eccentric contraction (2,3).  

BFR for Aerobic Capacity

This can be used for walking or cycling. If training for more than 3 weeks use this 1-3 times per week, if you are training for up to three weeks, you can do this 1-2 times per day.

• For a BFR cuff use 40-80% AOP, for a pBFR cuff use a tightness of 6-7 on a 1-10 scale.
• Perform walking or cycling exercise with the occlusion for 5-20 minutes per exercise at less than or equal to 50% VO2Max (2.3). 

BFR for Muscle Atrophy Prevention

1-2 times per day with 70%-100% arterial occlusion pressure (AOP) for a BFR cuff, and 8 on a 1-10 tightness scale for pBFR.

• Do 3-5 sets with 5-minute intervals of occlusion with 3-5 minutes of rest between each set. (2,3).  

Overall Takeaways of Blood Flow Restriction Training 

BFR/pBFR training can be very beneficial and useful when used for the right reason. This type of training should be perceived as a supplemental form of training and not a replacement. Athletes still need to complete HIT to experience neural drive and metabolic stress to achieve the desired gains.

But it has been shown to be beneficial when trying to prevent muscle atrophy, as well as make aerobic, hypertrophic, and strength gains without increased metabolic stress.  

References  

1. Abe, T., Fujita, S., Nakajima, T., Sakamaki, M., Ozaki, H., Ogasawara, R., Sugaya, M., Kudo, M., Kurano, M., Yasuda, T., Sato, Y., Ohshima, H., Mukai, C., & Ishii, N. (2010). Effects of Low-Intensity Cycle Training with Restricted Leg Blood Flow on Thigh Muscle Volume and VO2MAX in Young Men. Journal of sports science & medicine, 9(3), 452–458. 
2. Blood flow restriction training guidelines. Australian Sports Commission. (n.d.). https://www.ais.gov.au/position_statements/best_practice_content/blood-flow-restriction-training-guidelines 
3. (2020). Blood Flow Restriction Training: Strategies for Effective Applications. Retrieved December 2023, from https://www.nsca.com/education/videos/blood-flow-restriction training/.  
4. [P]rehab. (2022, December 13). Blood flow restriction training in a nutshell - the prehab guys. https://theprehabguys.com/blood-flow-restriction-training-in-a-nutshell/  
5. Rapid increase in plasma growth hormone after low-intensity resistance exercise with vascular occlusion  Yudai Takarada, Yutaka Nakamura, Seiji Aruga, Tetuya Onda, Seiji Miyazaki, and Naokata Ishii Journal of Applied Physiology 2000 88:1, 61-65  
6. Takarada, Y., Takazawa, & Ishii, N. (2000). Applications of vascular occlusion diminish disuse atrophy of knee extensor muscles. Medicine and Science in Sports and Exercise, 32(12), 2035–2039. https://doi.org/10.1097/00005768-200012000-00011  

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